Device to enable touchless operation

ABSTRACT

A device to enable touchless operation of an instrument is disclosed. The device includes an actuator configured to vibrate the instrument, a controller configured to control the actuator, and an interval detector configured to detect an interval between the instrument and an object to operate the instrument. The controller is configured to start vibrating the actuator having been still after the interval detected by the interval detector reaches a first threshold, keep vibrating the actuator until the interval detected by the interval detector reaches a second threshold larger than the first threshold after the interval reaches the first threshold, and stop vibrating the actuator after the interval detected by the interval detector reaches the second threshold.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2021-079203 filed in Japan on May 7,2021, the entire content of which is hereby incorporated by reference.

BACKGROUND

This disclosure relates to a technology to enable touchless operation ofan instrument.

To prevent fingerprints from sticking or contagious diseases fromspreading, there are known input devices that accept inputs withoutbeing touched on their touch surfaces. An example of such an inputdevice measures the electrostatic capacitance between a finger and atouch panel to detect the finger located a several centimeters away fromthe touch panel.

As another technology, JP 2017-072901 A discloses a tactile sensepresentation device for presenting an operational sense of a pushoperation by controlling a floating force given by a squeeze film to anoperating finger. The technique according to JP 2017-072901 A stops thevibration of the touch surface to allow the finger to touch the touchsurface when the interval between the finger and the touch surfacedecreases to less than a predetermined value. Such control of thefloating force caused by the squeeze film provides the user with anatural operational sense of a push operation.

SUMMARY

An aspect of this disclosure is a device to enable touchless operationof an instrument, the device including: an actuator configured tovibrate the instrument; a controller configured to control the actuator;and an interval detector configured to detect an interval between theinstrument and an object to operate the instrument. The controller isconfigured to: start vibrating the actuator having been still after theinterval detected by the interval detector reaches a first threshold;keep vibrating the actuator until the interval detected by the intervaldetector reaches a second threshold larger than the first thresholdafter the interval reaches the first threshold; and stop vibrating theactuator after the interval detected by the interval detector reachesthe second threshold.

An aspect of this disclosure is a device to enable touchless operationof an instrument, the device including: an actuator configured tovibrate the instrument a controller configured to control the actuator;and an interval detector configured to detect an interval between theinstrument and an object to operate the instrument. The controller isconfigured to: start vibrating the actuator having been still after theinterval detected by the interval detector reaches a first threshold;keep vibrating the actuator until a time elapsed since a last operationto the instrument reaches a time threshold; and stop vibrating theactuator after the elapsed time reaches the time threshold.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a configuration example of an inputdevice in an embodiment of this specification;

FIG. 2 is a cross-sectional diagram illustrating a configuration exampleof an input device in an embodiment of this specification;

FIG. 3 schematically illustrates temporal variation of the intervalbetween a finger and a touch surface measured by an interval detectorand temporal variation of the driving signal from an actuator drivercircuit to actuators;

FIG. 4A schematically illustrates a resonant mode of a cover glass;

FIG. 4B schematically illustrates another resonant mode of the coverglass;

FIG. 4C schematically illustrates still another resonant mode of thecover glass;

FIG. 5 illustrates an example of supplying an actuator with a drivingsignal with three different frequencies superimposed together;

FIG. 6 schematically illustrates temporal variation of the intervalbetween a finger and a touch surface measured by an interval detectorand temporal variation of the driving signal from an actuator drivercircuit to actuators;

FIG. 7 illustrates an example where image objects are displayed atlocations that do not overlap a node on a touch surface;

FIG. 8 illustrates a configuration example of a touch input panel;

FIG. 9A is an explanatory diagram illustrating a principle of generationof ozone; and

FIG. 9B is an explanatory diagram illustrating another principle ofgeneration of ozone.

EMBODIMENTS

Hereinafter, embodiments of this disclosure will be described withreference to the accompanying drawings. It should be noted that theembodiments are merely examples to implement this disclosure and are notto limit the technical scope of this disclosure. Some elements in thedrawings may be exaggerated in size or shape for clear understanding ofthe description.

Overview

The device in an embodiment of this specification disclosed hereinenables a user to operate an instrument without touching it directly.The device vibrates the instrument at high frequency to generate asqueeze film between the instrument and the object to operate theinstrument. The squeeze film enables the user to operate the instrumentwithout touching it directly. Hence, spread of contagious diseases orsticking of a fingerprint to the instrument can be prevented. Examplesof the instrument to be operated include a touch sensor, a button of anelevator or an automatic door, and a doorknob. A typical example of theobject to operate the instrument is a human part such as a finger or ahand.

As described above, the device in an embodiment of this specificationvibrates the instrument at high frequency. For this reason, lower powerconsumption of the device and a smaller possibility of failure in thedevice and the instrument are demanded. The device detects that anobject to operate the instrument, such as a finger, approaches a touchsurface of the instrument and vibrates the touch surface at highfrequency before the finger touches the touch surface to enable the userto operate the instrument without touching the touch surface with thefinger. The high-frequency vibration can be continued during the timethe finger is close to the touch surface or until a predetermined timeelapses since the last operation.

An embodiment of this specification measures the interval between theinstrument and the object to operate the instrument and controlsvibration based on the measured interval. For example, the device startsvibrating the instrument when the interval between the instrument andthe object to operate the instrument is reduced to a first threshold.The device stops the vibration when the interval once having reached thefirst threshold is increased to a second threshold larger than the firstthreshold. The vibration is kept until being stopped. In this way, thevibration is started after the measured interval reaches the firstthreshold and stopped after the measured interval subsequently reachesthe larger second threshold. This control enables touchless operationwhile attaining low power consumption and a small possibility offailure.

Another embodiment of this specification controls the vibration based onthe time elapsed since the last operation to the instrument. Forexample, the device starts vibrating the instrument when the intervalbetween the instrument and the object to operate the instrument isreduced to a threshold and stops the vibration when the time elapsedsince the last operation reaches a threshold. In this way, the vibrationis stopped after the time elapsed since the last operation reaches atime threshold. This control enables touchless operation while attaininglow power consumption and a small possibility of failure. The device canuse either one or both of the second threshold for the interval and thethreshold for the elapsed time. In using both thresholds, either ANDconditions or OR condition can be employed.

As described above, an embodiment of this specification generates asqueeze film between the instrument and the object to operate theinstrument to enable touchless operation of the instrument. In thefollowing, the squeeze film is explained.

It is known that a flat plate levitates when it is placed on a surfacevibrating at high frequency. This phenomenon is explained by squeezefilm pressure or acoustic radiation pressure. The pressure (levitationpressure) W/S the floating plate receives is expressed by the followingformula in accordance with the theory of acoustic radiation pressure:

W/S=(¼)(ρc ²)(ζ² /h ²),

where W represents the weight [N], S represents the area of the plate[m²], ρ represents the density of air [kg/m³], c represents the speed ofsound in air [m/s], ζ represents the amplitude of vibration of thesurface [m_(0-P)], and h represents the height of levitation [m].

Consider an example where the amplitude of vibration ζ of a surface is 5um, the height of levitation h is 5 um, and the levitation pressure is35.6 kPa. Assuming that the area of a fingertip is 1 cm², a force of 363gf acts on the finger as resistance to interfere with the finger intouching the surface.

Device Configuration

Hereinafter, embodiments of this specification are described using atouch input panel as an example of the instrument to be operated and afinger as an object to operate the touch panel. FIG. 1 schematicallyillustrates a configuration example of an input device in an embodimentof this specification. The input device includes a touch input panel 10,actuators 12, a main controller 21, an interval detector 23, an actuatordriver circuit 25, and a touch detector circuit 27. The main controller21, the interval detector 23, the actuator driver circuit 25, and thetouch detector circuit 27 are included in a controller of the inputdevice.

The actuators 12 vibrate the touch input panel 10 in the directionnormal to the touch surface (principal surface). In the configurationexample of FIG. 1, the actuators 12 are disposed on the left and theright of the touch input panel 10 on the front or the back of the touchinput panel 10. The side of the touch input panel 10 to be touched bythe user is defined as front and the opposite side as back. Theactuators 12 can be fabricated directly on the substrate of the touchinput panel 10 by semiconductor process or they can be fabricatedseparately from the substrate and bonded to the substrate.

The touch input panel can be vibrated in the direction normal to thetouch surface by using the elongation vibration mode or the thicknessvibration mode of a planar piezoelectric member bonded to the touchinput panel. The number and the shapes of actuators 12 and the locationsto dispose the actuators 12 can be determined by design so that thetouch input panel 10 will vibrate in a predetermined vibration mode.

The actuator driver circuit 25 drives the actuators 12. The actuators 12can be made of desirable kinds of material and can have a desirablestructure. For example, the actuators 12 can be thin-film actuatorsfabricated on a substrate and they can be of any kind of actuators, suchas piezoelectric actuators, macro-fiber composite actuators, smartmaterial actuators, or electronic polymer actuators. The plurality ofactuators 12 can be made of the same or different material and can havethe same or different structures.

The actuator driver circuit 25 can vibrate the actuators 12 at adesirable vibration frequency by supplying the actuators 12 with adriving signal (driving voltage) at a specific frequency. The touchinput panel 10 vibrates with the vibration of the actuators 12 togenerate a squeeze film.

The touch input panel 10 utilizes pressure or capacitance to output asignal indicating a location (touch point or operation point) on thetouch surface touched by a finger directly or through a squeeze film tothe touch detector circuit 27. The touch input panel 10 can employ anyinput method in accordance with the design. The touch detector circuit27 drives the touch detector electrodes of the touch input panel 10 anddetects the user's operation point on the touch surface based on thetouch detection signal from the touch input panel 10.

The interval detector 23 detects a finger close to the touch surface ofthe touch input panel 10 and measures the interval between the fingerand the touch surface. The interval detector 23 can employ any kind ofexisting technology, such as a hover detection function of a capacitancetouch panel, a visible-light camera, an infrared camera, a pyroelectricsensor, or an ultrasonic sensor.

For example, the interval detector 23 measures the interval by taking animage of light illuminating the finger with a camera. The intervaldetector 23 can measure the interval by emitting a random dot patternfrom an infrared projector and reading the variation after the dotpattern hits the finger with an infrared camera. Alternatively, theinterval detector 23 can measure the interval by analyzing the timetaken by emitted infrared rays to hit the finger and return. Theinterval detector 23 can also measure the interval by taking images ofthe reflection of the light hitting the finger with a plurality ofcameras and analyzing the images from the cameras.

In another configuration example, the interval detector 23 measures theinterval between the finger and the touch surface based on theelectrostatic capacitances between electrodes included in the touchpanel. The interval detector 23 is incorporated in the touch detectorcircuit 27. For example, the touch input panel 10 includes a pluralityof transmitter electrodes, a plurality of receiver electrodes, and fourperipheral electrodes. To detect an approaching finger, the touchdetector circuit 27 emits electric fields from all transmitterelectrodes and opens all receiver electrodes. The touch detector circuit27 serially senses the received signals with the four peripheralelectrodes. The touch detector circuit 27 determines the interval to thefinger and the orientation of the finger based on the level values ofthe received signals.

In still another configuration example, the interval detector 23 uses apyroelectric sensor. The pyroelectric sensor outputs a pulse signal whenthe temperature therearound varies. That is to say, the pyroelectricsensor outputs a pulse signal when a human body enters an area within apredetermined distance or a human body moves within such an area. Inresponse to the first response signal from the pyroelectric sensor, themain controller 21 drives the actuators 12 by controlling the actuatordriver circuit 25. The main controller 21 maintains the vibration of theactuators 12 until no responding period of the pyroelectric sensorreaches a predetermined length (for example, 20 seconds).

The main controller 21 controls the interval detector 23, the actuatordriver circuit 25, and the touch detector circuit 27. The maincontroller 21 controls the actuator driver circuit 25 to generate asqueeze film depending on the interval between a finger and the touchsurface measured by the interval detector 23. The main controller 21further sends the locational information detected by the touch inputpanel 10 to an external host apparatus. The details of the method forthe main controller 21 to control the actuators 12 will be describedlater.

FIG. 2 is a cross-sectional diagram illustrating a configuration exampleof an input device in an embodiment of this specification. A housing box17 is fixed to a cover glass 13 and a display 15 is placed in thehousing box 17. A touch sensor 11 is disposed between the cover glass 13and the display 15. The touch sensor 11 is bonded on the backside of thecover glass 13. For example, photoelastic resin can be used to bond thetouch sensor 11 and the cover glass 13.

In this example, the touch sensor 11 and the cover glass 13 constitute atouch input panel 10. As described with reference to FIG. 1, the touchsensor 11 detects a touch of a pointer such as a finger and locates thecoordinates of the touch. The touch sensor 11 can further have functionsto detect an approaching pointer and measure the interval to thepointer. The interval measurement can be performed by the intervaldetector 23 not shown in FIG. 2.

The front side of the cover glass 13 is a touch surface. The actuators12 are fixed to the backside of the cover glass 13. The actuators 12 inthe configuration example of FIG. 2 are located outer than the touchsensor 11 on the backside of the cover glass 13. The actuators 12 can bedisposed on the surface of the touch sensor 11.

The actuator driver circuit 25 not shown in FIG. 2 supplies a voltagesignal at a specific frequency to the actuators 12 to vibrate the coverglass 13. The actuators 12 can be disposed at locations off the nodes ofdisplacement in the vibration of the cover glass 13. In other words, theactuators 12 can be disposed so that the actuators 12 are not on thenodes. As a result, the cover glass 13 can be vibrated effectively bythe vibration of the actuators 12.

In contrast, the cover glass 13 can be bonded with the housing box 17 inthe area including the locations to be the nodes of displacement of thecover glass 13. This configuration enables the cover glass 13 to vibratemore appropriately. The nodes of displacement of the touch surface arethe locations to show zero amplitude in the vibration mode of the touchsurface.

A space is provided between the cover glass 13 and the display 15 tovibrate the cover glass 13 efficiently. The space between the coverglass 13 and the display 15 can be filled with photoelastic resin.

Vibration Control

Hereinafter, vibration control for the actuators 12 is described. Themain controller 21 controls vibration of the actuators 12 with theactuator driver circuit 25 based on the interval measured by theinterval detector 23.

FIG. 3 schematically illustrates temporal variation of the intervalbetween a finger and the touch surface measured by the interval detector23 and temporal variation of the driving signal from the actuator drivercircuit 25 to the actuators 12. The graph 31 provides temporal variation35 of the measured interval between a finger and the touch surface. Thegraph 32 provides temporal variation 36 of the driving signal from theactuator driver circuit 25 to the actuators 12.

In the graph 31, the horizontal axis represents time and the verticalaxis represents the interval measured by the interval detector 23 (thedevice output). In the graph 32, the horizontal axis represents time andthe vertical axis represents the output from the actuator driver circuit25. It is assumed that the actuators 12 are piezoelectric actuators andthey vibrate at the same frequency as the output from the actuatordriver circuit 25.

As illustrated in the graph 31, a finger approaches the touch surfacefrom a distance and the value measured by the interval detector 23reaches a predetermined first threshold at a time T1. As illustrated inthe graph 32, the main controller 21 makes the actuator driver circuit25 start outputting a driving signal in response to the measuredinterval reduced to the first threshold. As a result, the actuators 12start vibrating and further, the touch surface of the touch input panel10 starts vibrating together. As understood from this description, thetouch surface starts vibrating after the measured interval decreases tothe first threshold.

The interval detector 23 outputs a signal in accordance with theinterval between the touch surface of the touch input panel 10 and theuser's finger. The main controller 21 controls the actuator drivercircuit 25 to start vibrating the actuators 12 when the signal (measuredinterval) from the interval detector 23 decreases to the firstthreshold, so that the touch surface of the touch input panel 10vibrates in a specific frequency band.

At a time T2 later than the time T1, the measured interval between thefinger and the touch surface reaches a second threshold. The secondthreshold is a predetermined value larger than the first threshold.Before reaching the second threshold at the time T2, the measuredinterval is always smaller than the second threshold. In response to themeasured interval reaching the second threshold, the main controller 21makes the actuator driver circuit 25 stop outputting the driving signalas illustrated in the graph 32. As a result, the actuators 12 stopvibrating and further, the touch surface of the touch input panel 10stops vibrating together. As understood from this description, the touchsurface stops vibrating after the measured interval increases to thesecond threshold.

The touch input panel 10 is vibrated at a frequency at which a squeezefilm is generated between the finger and the touch surface and touchoperation (input operation) with the finger works without a direct touchon the touch surface. The vibration frequency of the touch input panel10 can be included in a frequency band from 10 kHz to 150 kHz or from 15kHz to 100 kHz. The first threshold and the second threshold aredetermined appropriately for the configuration of the input device. Forexample, the first threshold can be in a range from 5 cm to 10 cm andthe second threshold can be 1.5 times to twice as large as the firstthreshold.

As described above, the vibration of the actuator 12 is maintained fromthe time the measured interval has decreased to the first thresholduntil it increases to the second threshold. This configurationeffectively prevents or reduces direct touches of a finger to the touchsurface during the touch operation with the finger.

As described above, this example does not vibrate the actuators 12 untilthe measured interval decreases to the first threshold and startsvibrating the actuators 12 when the measured interval reaches the firstthreshold. Furthermore, this example stops vibrating the actuators 12when the measured interval reaches the second threshold.

Maintaining vibration while the finger is close to the touch surfaceeffectively prevents or reduces direct touches of a finger to the touchsurface. Stopping the vibration when the measured interval indicatesthat the finger is sufficiently distant from the touch surface and touchoperation is not intended reduces the power consumption and thepossibility of failure.

As described above, the second threshold as a condition to stopvibration is larger than the first threshold. The user may move thefinger up and down (away from and closer to the touch surface) duringthe touch operation. Determining the second threshold to stop vibrationto be larger than the first threshold to start vibration can prevent thevibration of the actuators 12 from being frequently started/stoppedduring the user's touch operation. The second threshold can be equal tothe first threshold.

The foregoing example stops vibrating the actuators 12 based on themeasured interval. Another example can stop vibrating the actuators 12based on the time elapsed since the last operation, instead of or inaddition to the measured interval.

The main controller 21 counts the time elapsed since the last user'soperation to the touch input panel 10. When the elapsed time reaches apredetermined time threshold, the main controller 21 stops vibrating theactuator 12. This configuration of stopping the vibration based on thetime elapsed since the last operation to the touch input panel 10 canstop the vibration when the user's operation is finished and there is asmall possibility that a finger will touch the touch surface. As aresult, the power consumption and the possibility of failure can bereduced.

The touch detector circuit 27 has a function to detect a touch(touch-on) of a pointer (such as a finger) to the touch input panel andleaving (touch-off) of the pointer from the touch input panel andtherefore, the time elapsed since detection of the pointer leaving canbe used as the aforementioned time elapsed since the last operation.

For example, the main controller 21 stops vibrating the actuators 12 atleast either when the measured interval reaches the second threshold orwhen the time elapsed since the last operation reaches a time threshold.In another example, the main controller 21 stops vibrating the actuators12 when the measured interval is the second threshold or more and theelapsed time is the time threshold or more.

In the example illustrated in FIG. 3, the amplitude and the frequency ofthe output from the actuator driver circuit 25 are fixed. As describedabove, the levitation force from a squeeze film increases with decreaseof the interval between a finger and the touch surface. Accordingly,this configuration effectively prevents or reduces direct touches of afinger to the touch surface. In another example, either one or both ofthe frequency and the amplitude of vibration can be varied in thevibration period from the time T1 to the time T2.

Next, an example of the method of driving the actuators 12 is described.The output signal from the actuator driver circuit 25 in the exampleillustrated in FIG. 3 can be a single-frequency sine wave. When theactuators 12 vibrate at a single specific frequency, the touch surfacevibrates in a vibration mode (resonant mode) in accordance with thevibration of the actuators 12.

FIGS. 4A to 4C schematically illustrate different resonant modes of thecover glass 13. FIG. 4A schematically illustrates the displacement in aresonant mode at 15.7 kHz; FIG. 4B schematically illustrates thedisplacement in a resonant mode at 19.4 kHz; and FIG. 4C schematicallyillustrates the displacement in a resonant mode at 17.8 kHz. In eachresonant mode, a standing wave is generated on the cover glass 13 andtheir nodes and antinodes occur at specific locations within the plane.

In FIG. 4A, black lines represent the nodes of the standing wave. One ofthe nodes is provided with a reference sign 41 in FIG. 4A. Each node 41extends in the Y-axis direction. The nodes 41 appear at regularintervals in the X-axis direction only. The X-axis and the Y-axis areperpendicular to each other within the plane of the touch surface.

In FIG. 4B, black lines represent the nodes of the standing wave. One ofthe nodes is provided with a reference sign 42 in FIG. 4B. Each node 42extends in the X-axis direction. The nodes 42 appear at regularintervals in the Y-axis direction only. In FIG. 4C, black regionsrepresent the nodes of the standing wave. In FIG. 4C, grid-like nodesoccur.

The parts corresponding to the nodes in the vibrating cover glass 13 donot displace in the direction normal to the touch surface (principalsurface). Accordingly, no squeeze film is generated above the nodes; thelevitation force for the finger there could be too small to besufficient for touchless operation.

Frequency Control

The main controller 21 in an embodiment of this specification vibratesthe touch surface with a plurality of frequencies (resonant modes). Inthe following, two methods to vibrate the touch surface with a pluralityof frequencies (resonant modes) are described.

The first method drives the actuators 12 with superimposed multiplefrequencies. In accordance with the vibration of the actuators 12 in astate where vibrations at different frequencies are superimposedtogether, the touch surface vibrates in a state where multiple resonantmodes are superimposed together. This configuration reduces node areasfrom the touch surface.

The second method drives the actuators 12 at multiple frequencies bytime division. In other words, this method vibrates the actuators 12 atdifferent frequencies cyclically. In accordance with the vibration ofthe actuators 12, the touch surface cyclically changes its resonantmode. As a result, the finger is provided with an appropriate levitationforce in one of the resonant modes.

An example of superimposition driving (the first method) is described.FIG. 5 illustrates an example of supplying an actuator 12 with a drivingsignal of three different frequencies superimposed together. Theactuator driver circuit 25 superimposes a 15.7 kHz signal, a 17.8 kHzsignal, and a 19.4 kHz signal together to generate an output drivingsignal and supplies the output driving signal to the actuator 12. Theactuator 12 vibrates similarly to the supplied driving signal.

In the case where the actuator driver circuit 25 generates an outputdriving signal by superimposing two signals of the 15.7 kHz signal andthe 19.4 kHz signal together and supplies the output driving signal tothe actuators 12, the displacement occurring to the cover glass is suchthat the displacement to occur in the cover glass when the actuators 12are driven with only the 15.7 kHz signal is added to the displacement tooccur in the cover glass when the actuators 12 are driven with only the19.4 kHz signal.

Accordingly, in the case where the actuator driver circuit 25 generatesan output driving signal by superimposing two signals of a 15.7 kHzsignal and a 19.4 kHz signal together and supplies the output signal tothe actuators 12, the displacement of the cover glass at the location ofa node when the actuators 12 are driven with only the 15.7 kHz signal isequal to the displacement when the actuators 12 are driven with only the19.4 kHz signal.

In view of this result, in the case where the actuator driver circuit 25generates an output driving signal by superimposing two signals of a15.7 kHz signal and a 19.4 kHz signal together and supplies the outputsignal to the actuators 12, the locations where displacement does notoccur or the locations to be a node are expressed by the logical AND ofthe diagram representing the nodes when the actuators 12 are driven withonly the 15.7 kHz signal and the diagram representing the nodes when theactuators 12 are driven with only the 19.4 kHz.

In other words, in the case where the actuator driver circuit 25generates an output driving signal by superimposing two signals of a15.7 kHz signal and a 19.4 kHz signal together and supplies the outputsignal to the actuators 12, the location where displacement still doesnot occur or the locations remaining as nodes are the grid points wherethe nodes in FIG. 4A and the nodes in FIG. 4B diagrammaticallyintersect.

If the actuator driver circuit 25 drives the actuators 12 with a drivingsignal with another 17.8 kHz signal superimposed on the foregoing outputdriving signal, the nodes occurring at the grid points where the nodesin FIGS. 4A and 4B diagrammatically intersect become no longer nodesbecause of the superposition principle of waves, so that the cover glasscan be displaced in the normal direction. Through the Inventors'experiments, it was revealed that the entire cover glass can bedisplaced in the normal direction and provides a finger with asufficient levitation force for touchless operation by supplying theactuators 12 with an output driving signal generated by superimposing a15.7 kHz signal, a 17.8 kHz signal, and a 19.4 kHz signal together asdescribed above.

As described with reference to FIGS. 4A to 4C, the resonant modes at theforegoing three frequencies exhibit different node layouts. Accordingly,vibration at superimposed these three frequencies can effectively reducethe node areas from the touch surface.

As described above, the nodes in the resonant mode at 15.7 kHz occur atregular intervals in the X-axis direction (the first direction) only andthe nodes in the resonant mode at 19.4 kHz occurs at regular intervalsin the Y-axis direction (the second direction) only. The nodes in theresonant mode at 17.8 kHz occurs at regular intervals in both the X-axisdirection and the Y-axis direction. The combination of such threeresonant modes effectively reduces the area of nodes.

The number of frequencies to be superimposed and their values can bedetermined appropriately for the configuration of the input device. Thenumber of frequencies to be superimposed can be four or more and thenode layouts in the different resonant modes are not also limited tospecific ones. The frequencies to be superimposed can be preset to themain controller 21 or the actuator driver circuit 25. The actuatordriver circuit 25 can output a driving signal of superimposed multiplefrequencies in response to an instruction from the main controller 21 tostart vibration or the main controller 21 can specify the frequencies tobe superimposed in the instruction for the actuator driver circuit 25.

Next, an example of time division driving (the second method) isdescribed. The actuator driver circuit 25 changes the frequency of thedriving signal cyclically, for example, at every 1 millisecond. Theactuator driver circuit 25 serially and cyclically outputs drivingsignals of predetermined different frequencies. Assume that threefrequencies of 15.7 kHz, 17.8 kHz, and 19.4 kHz are preset. The actuatordriver circuit 25 selects the frequencies for the output driving signalin the order of 15.7 kHz, 17.8 kHz, and 19.4 kHz. The actuator drivercircuit 25 selects 15.7 kHz next to 19.4 kHz.

The number of frequencies for the signals to be serially output andtheir values are determined appropriately for the configuration of theinput device. The frequencies for the signals to be serially output canbe preset to the main controller 21 or the actuator driver circuit 25.The actuator driver circuit 25 can cyclically output driving signals ofdifferent frequencies in response to an instruction from the maincontroller 21 to start vibration or the main controller 21 can specifythe frequency for the driving signal to be output next in theinstruction for the actuator driver circuit 25.

Amplitude Control

Next, an example of a driving method that varies the driving voltage(amplitude of vibration) for the actuators 12 with time to generate asqueeze film is described. This driving method more appropriatelyprovides a necessary levitation force to a finger while attaining lowpower consumption and a small possibility of failure.

When a finger approaches the touch surface, the main controller 21starts vibrating the actuators 12 having been still. Thereafter, as themeasured interval between the touch surface and the finger decreasesfurther, the main controller 21 increases the output voltage from theactuator driver circuit 25 or the amplitude of vibration of theactuators 12. Inversely, as the measured interval between the touchsurface and the finger increases, the main controller 21 reduces theoutput voltage from the actuator driver circuit 25.

FIG. 6 schematically illustrates temporal variation of the intervalbetween a finger and the touch surface measured by the interval detector23 and temporal variation of the driving signal from the actuator drivercircuit 25 to the actuators 12. The graph 61 provides temporal variation65 of the measured interval between a finger and the touch surface. Thegraph 62 provides temporal variation 66 of the driving signal from theactuator driver circuit 25 to the actuators 12.

In the graph 61, the horizontal axis represents time and the verticalaxis represents the interval measured by the interval detector 23 (thedevice output). The first threshold and the second threshold can be thesame as those in the example described with reference to FIG. 3. In thegraph 62, the horizontal axis represents time and the vertical axisrepresents the output from the actuator driver circuit 25.

As illustrated in the graph 61, a finger approaches the touch surfacefrom a distance and the value measured by the interval detector 23reaches a predetermined first threshold at a time T11. As illustrated inthe graph 62, the main controller 21 makes the actuator driver circuit25 start outputting a driving signal in response to the measuredinterval reduced to the first threshold. As a result, the actuators 12start vibrating and further, the touch surface of the touch input panel10 starts vibrating together.

The measured interval between the finger and the touch surface decreasesfrom the time T11 to a time T12 as illustrated in the graph 61. The maincontroller 21 increases the voltage of the driving signal in response tothe decrease in measured interval as illustrated in the graph 62. Themeasured interval is unchanged from the time T12 to a time T13 asillustrated in the graph 61. During this period, the finger receives aresistance because of the squeeze film pressure or acoustic radiationpressure and levitates in the air slightly above the touch surface. Thedriving signal voltage is constant from the time T12 to the time T13 asillustrated in the graph 62.

The measured interval between the finger and the touch surface increasesfrom the time T13 and a time T14 as illustrated in the graph 61. Themain controller 21 reduces the voltage of the driving signal in responseto the increase in the measured interval as illustrated in the graph 62.

The measured interval between the finger and the touch surface decreasesfrom the time T14 to a time T15 as illustrated in the graph 61. The maincontroller 21 increases the voltage of the driving signal in response tothe decrease in measured interval as illustrated in the graph 62. Themeasured interval is unchanged from the time T15 to a time T16 asillustrated in the graph 61. The driving signal voltage is constant fromthe time T15 to the time T16 as illustrated in the graph 62.

The measured interval between the finger and the touch surface increasesfrom the time T16 and a time T17 as illustrated in the graph 61. Themain controller 21 reduces the voltage of the driving signal in responseto the increase in the measured interval as illustrated in the graph 62.

The measured interval reaches the second threshold at the time T17 andthereafter, increases further as illustrated in the graph 61. The maincontroller 21 stops outputting the driving signal at the time T17 asillustrated in the graph 62. As a result, the actuators 12 stopvibrating and further, the touch surface of the touch input panel 10stops vibrating together.

The above-described amplitude control can be combined with either of theforegoing frequency control methods. The main controller 21 controls theamplitude of vibration based on the measured interval and further, makesthe actuator driver circuit 25 output a driving signal with multiplefrequencies superimposed together or output driving signals of differentfrequencies cyclically to the actuators 12. The driving signal can be asingle-frequency signal.

The increase rate and the decrease rate for the amplitude for a measuredinterval can be different and they can be fixed rates or variable rates.

Other Control Methods

Hereinafter, other methods of controlling the input device aredescribed. The main controller 21 in an embodiment of this specificationinfers a touch point of a finger to operate the input device anddetermines the driving signal for the actuators 12 based on the inferredlocation. Specifically, the main controller 21 selects a singlefrequency or a plurality of frequencies to be superimposed for thedriving signal. More specifically, the main controller 21 selects one ormore frequencies so that the inferred touch point will not overlap thenodes in the vibration mode of the touch surface. This configurationreduces the possibility that the finger will directly touch the touchsurface to operate the input device.

The interval detector 23 can detect the location of a finger within thetouch surface, in addition to the interval between the finger and thetouch surface. As described above, any existing technique to locate anin-plane point can be employed.

For example, the main controller 21 has control information fordifferent vibration modes. The control information for one vibrationmode includes information on one or more frequencies for a drivingsignal to generate the vibration mode and the node areas in thevibration mode. The main controller 21 acquires not only information onthe interval between a finger and the touch surface but also informationon the location of the finger in the touch surface from the intervaldetector 23. For example, the main controller 21 can infer that anin-plane location of a finger at the time when the interval between thetouch surface and the finger reaches a predetermined threshold is atouch point. The touch point is a location where operation of touchinput with a finger is performed.

The main controller 21 compares the node areas of each vibration modedefined in the control information with the inferred touch point andselects a vibration mode whose node areas do not include the inferredtouch point. The main controller 21 determines the one or morefrequencies associated with the selected vibration mode to be the one ormore frequencies to generate an actuator driving signal.

The input device in an embodiment of this specification displays imageobjects to be touched for operation on the display 15 at the locationsoutside the node areas of the vibration mode. Since the frequency forthe driving signal to vibrate the actuators 12 is predetermined, thenode areas of the touch surface in the vibration mode are also known inadvance.

FIG. 7 illustrates an example where objects to be touched for operationare displayed outside the node areas of the vibration mode. The touchinput panel 10 has nodes (also referred to as node area) 105 indicatedby dashed lines. In the example of FIG. 7, grid-like nodes appear on thetouch input panel 10. The display 15 displays objects 106 to be operatedby a user so that the objects do not overlap the nodes of vibration ofthe touch input panel 10. In FIG. 7, one of the four objects is providedwith a reference sign 106 by way of example.

The main controller 21 supplies image data to the display 15. The imageaccording to the image data includes one or more objects to be touchedfor operation. Each object is displayed in an area that does not overlapthe predefined node area (an area outside the node area). Since eachobject is located in an area that does not overlap the node area, thetouch input panel 10 can effectively provide a levitation force to afinger approaching to touch an object.

Ozone Generator

Hereinafter, an example of a touch input panel that generates ozone isdescribed. Ozone can sterilize the touch surface. When the touch surfaceis contaminated, sterilizing the touch surface with ozone can preventcontagious diseases from spreading.

FIG. 8 illustrates a configuration example of a touch input panel 10.The section 81 is a plan diagram of an electrode board 101 of the touchinput panel 10; the section 82 is a partial enlarged diagram of the plandiagram 81; and the section 83 is an A-A′ cross-sectional diagram of thepartial enlarged diagram 82. The electrode board 101 includes Xelectrodes 201, Y electrodes 202, and insulating films 203 above atransparent support substrate 310.

In the sections 81 and 82, the X electrodes 201 and the lines thereforare denoted by dotted lines and the Y electrodes 202 and the linestherefor are denoted by solid lines. The X electrodes and the Yelectrodes are transparent electrodes; they can be made of indium tinoxide (ITO), for example. These X electrodes 201 and Y electrodes 202can have quadrangular planar shapes.

The touch detector circuit 27 applies a predetermined voltage across theX electrodes 201 and the Y electrodes 202 to drive the electrode board101 as an ozone generator. In response to the application of voltage,ozone is generated on the surface of the electrode board 101 tosterilize the surface 101 a of the electrode board 101.

The main controller 21 controls the application of voltage by the touchdetector circuit 27. Specifically, the main controller 21 instructs thetouch detector circuit 27 to apply voltage to the electrode board 101 orstop the application of voltage to the electrode board 101 in responseto an external input such as a signal from a sensor (not shown) or anoperation by a user.

The electrode board 101 is described in more detail. In the section 81,the lines for the X electrodes 201 and the lines for the Y electrodes202 are connected with terminals 301 and 302, respectively. Theterminals 301 and 302 are connected with the touch detector circuit 27.

The X electrodes 201 and the Y electrodes 202 can have quadrangular(rhombic or rectangular) shapes. A plurality of X electrodes 201 areconnected by bridge electrodes 311X as first connection members (see thesection 82) into a string extending in the x-direction. That is to say,a plurality of X electrodes 201 are aligned in the x-direction. These Xelectrodes electrically connected in the x-direction are referred to asan X-electrode set. The X-electrode sets connected in strings in thex-direction are disposed at 2-mm intervals in the y-direction, forexample. Each X-electrode set extends in parallel in the y-direction tothe other X-electrode sets.

A plurality of Y electrodes 202 are connected by bridge electrodes 311Yas second connection members (see the section 82) into a stringextending in the y-direction. That is to say, a plurality of Yelectrodes 202 are aligned in the y-direction. These Y electrodeselectrically connected in the y-direction are referred to as aY-electrode set. The Y-electrode sets connected in strings in they-direction are disposed at 2-mm intervals in the x-direction, forexample. Each Y-electrode set extends in parallel in the x-direction tothe other Y-electrode sets.

The X-electrode sets and the Y-electrode sets are fabricated in such amanner that each first connection member (bridge electrode 311X)overlaps a second connection member (bridge electrode 311Y) with aninsulating film 203 interposed therebetween when viewed planarly. Asillustrated in the section 83, a bridge electrode 311X and a bridgeelectrode 311Y are isolated from each other by an insulating film 203.In other words, an X-electrode set and a Y-electrode set cross eachother in three dimensions with an insulating film 203 interposedtherebetween. The X electrodes 201 and the Y electrodes 202 arefabricated in such a manner that they do not overlap when viewedplanarly. In other words, each X electrode 201 is adjacent to Yelectrodes 202 when viewed planarly.

Next, a manufacturing method is described using the section 83. Thesupport substrate 310 is a transparent insulating substrate such as aglass substrate. First, the method produces bridge electrodes 311X,which are films of a transparent conductor such as ITO, on the firstsurface 310 a of the support substrate 310. Next, the method producesinsulating films 203, which can be films of silicon nitride (SiN), abovethe bridge electrodes 311X.

Each insulating film 203 is formed so that the insulating film 203covers a part of a bridge electrode 311X to isolate the bridge electrode311X from a Y electrode 202 and a bridge electrode 311Y but does notcover another part of the bridge electrode 311X to let the bridgeelectrode 311X contact the X electrode 201. Next, the method produces Xelectrodes 201, Y electrodes 202, bridge electrodes 311Y, lines, andterminals 301 and 302 together. These are transparent conductive films.Last of all, the method produces an insulating film 312, which can be aSiN film, and opens contact holes in the terminals 301 and 302.

Application of a voltage across the terminals 301 and 302 on theelectrode board 101 fabricated as described above generates electricfields between X-electrode sets and Y-electrode sets. When the intensityof the generated electric fields exceeds the air breakdown level, ozoneis generated by electric discharge. The locations on the insulating film312 where ozone is generated can be single-layer areas betweenelectrodes such as an area 321 between an X electrode 201 and a Yelectrode 202 and multi-layered areas between electrodes such as an area322 between a bridge electrode 311X and a bridge electrode 311Y with aninsulating film 203 therebetween.

FIGS. 9A and 9B are explanatory diagrams illustrating principles ofgeneration of ozone. FIG. 9A illustrates the principle of generation ofozone in an electric field generation area 321 of a single-layer areabetween electrodes in the section 82 and FIG. 9B illustrates theprinciple of generation of ozone in an electric field generation area322 of a multi-layered area between electrodes in the section 83. Thesignal source 401 is an alternating-current source to apply a voltage tothe X electrode 201 and the signal source 402 is an alternating-currentsource to apply a voltage to the Y electrode 202.

Assume that the output from the signal source 401 is GND and the outputfrom the signal source 402 is a predetermined alternating voltage. Inthis case, an electric field 410 is generated in the single-layer areabetween electrodes in FIG. 9A because of the potential differencebetween the X electrode 201 and the Y electrode 202 and an electricfield 420 is generated in the multi-layered area between electrodes inFIG. 9B because of the potential difference between the bridge electrode311X and the bridge electrode 311Y. When the intensities of the electricfields 410 and 420 in the air above the insulating film 312 reach apredetermined value, air breakdown happens. The air breakdown inducessilent discharge that generates ozone.

As set forth above, embodiments of this disclosure have been described;however, this disclosure is not limited to the foregoing embodiments.Those skilled in the art can easily modify, add, or convert each elementin the foregoing embodiments within the scope of this disclosure. A partof the configuration of one embodiment can be replaced with aconfiguration of another embodiment or a configuration of an embodimentcan be incorporated into a configuration of another embodiment.

What is claimed is:
 1. A device to enable touchless operation of aninstrument, the device comprising: an actuator configured to vibrate theinstrument; a controller configured to control the actuator; and aninterval detector configured to detect an interval between theinstrument and an object to operate the instrument, wherein thecontroller is configured to: start vibrating the actuator having beenstill after the interval detected by the interval detector reaches afirst threshold; keep vibrating the actuator until the interval detectedby the interval detector reaches a second threshold larger than thefirst threshold after the interval reaches the first threshold; and stopvibrating the actuator after the interval detected by the intervaldetector reaches the second threshold.
 2. The device according to claim1, wherein the controller is configured to vibrate the actuator within afrequency band from 10 kHz to 150 kHz.
 3. The device according to claim1, wherein the instrument is a touch input panel, and wherein thecontroller is configured to drive the actuator in such a way that theactuator vibrates in a state where a plurality of frequencies aresuperimposed together.
 4. The device according to claim 3, wherein atouch surface of the touch input panel vibrates in a state where aresonant mode in which nodes occur only in a first direction within atouch surface of the touch input panel, a resonant mode in which nodesoccur only in a second direction perpendicular to the first directionwithin the touch surface, and a resonant mode in which nodes occur inboth the first direction and the second direction within the touchsurface are superimposed together in response to vibration of theactuator.
 5. The device according to claim 1, wherein the controller isconfigured to vibrate the actuator at different frequencies cyclically.6. The device according to claim 5, wherein the instrument is a touchinput panel, and wherein a touch surface of the touch input panelvibrates in one of a resonant mode in which nodes occur only in a firstdirection within a touch surface of the touch input panel, a resonantmode in which nodes occur only in a second direction perpendicular tothe first direction within the touch surface, and a resonant mode inwhich nodes occur in both the first direction and the second directionwithin the touch surface in accordance with vibration of the actuator.7. The device according to claim 1, wherein the controller is configuredto increase an amplitude of vibration of the actuator as the objectapproaches the instrument and decrease the amplitude of vibration of theactuator as the object gets away from the instrument.
 8. The deviceaccording to claim 1, wherein the controller is configured to stopvibrating the actuator in a case where an interval detected by theinterval detector is the second threshold or more and a time elapsedsince the last operation to the instrument is the time threshold ormore.
 9. The device according to claim 1, wherein the instrument is atouch input panel, and wherein the controller is configured to: detect alocation of the object within a touch surface of the touch input panel;infer a touch point of the object based on the detected location; anddrive the actuator with a driving signal with which the inferred touchpoint is located outside nodes of vibration of the touch surface. 10.The device according to claim 1, further comprising: a displayconfigured to display an image; wherein the instrument is a touch inputpanel disposed in front of the display, and wherein the controller isconfigured to display image objects to be touched for operation on thedisplay in areas outside nodes of vibration of the touch surface of thetouch input panel.
 11. The device according to claim 1, wherein theinstrument is a touch input panel including elements configured togenerate ozone.
 12. A device to enable touchless operation of aninstrument, the device comprising: an actuator configured to vibrate theinstrument; a controller configured to control the actuator; and aninterval detector configured to detect an interval between theinstrument and an object to operate the instrument, wherein thecontroller is configured to: start vibrating the actuator having beenstill after the interval detected by the interval detector reaches afirst threshold; keep vibrating the actuator until a time elapsed sincea last operation to the instrument reaches a time threshold; and stopvibrating the actuator after the elapsed time reaches the timethreshold.
 13. The device according to claim 12, wherein the controlleris configured to vibrate the actuator within a frequency band from 10kHz to 150 kHz.
 14. The device according to claim 12, wherein theinstrument is a touch input panel, and wherein the controller isconfigured to drive the actuator in such a way that the actuatorvibrates in a state where a plurality of frequencies are superimposedtogether.
 15. The device according to claim 14, wherein a touch surfaceof the touch input panel vibrates in a state where a resonant mode inwhich nodes occur only in a first direction within a touch surface ofthe touch input panel, a resonant mode in which nodes occur only in asecond direction perpendicular to the first direction within the touchsurface, and a resonant mode in which nodes occur in both the firstdirection and the second direction within the touch surface aresuperimposed together in response to vibration of the actuator.
 16. Thedevice according to claim 12, wherein the controller is configured tovibrate the actuator at different frequencies cyclically.
 17. The deviceaccording to claim 16, wherein the instrument is a touch input panel,and wherein a touch surface of the touch input panel vibrates in one ofa resonant mode in which nodes occur only in a first direction within atouch surface of the touch input panel, a resonant mode in which nodesoccur only in a second direction perpendicular to the first directionwithin the touch surface, and a resonant mode in which nodes occur inboth the first direction and the second direction within the touchsurface in accordance with vibration of the actuator.
 18. The deviceaccording to claim 12, wherein the instrument is a touch input panel,and wherein the controller is configured to: detect a location of theobject within a touch surface of the touch input panel; infer a touchpoint of the object based on the detected location; and drive theactuator with a driving signal with which the inferred touch point islocated outside nodes of vibration of the touch surface.
 19. The deviceaccording to claim 12, further comprising: a display configured todisplay an image; wherein the instrument is a touch input panel disposedin front of the display, and wherein the controller is configured todisplay image objects to be touched for operation on the display inareas outside nodes of vibration of the touch surface of the touch inputpanel.
 20. The device according to claim 12, wherein the instrument is atouch input panel including elements configured to generate ozone.